The first and second phases of the study of "Peripheral Arterial Disease in the Diabetic" have been completed. A total of 707 study subjects were recruited and studied in the first phase. In the second phase repeat studies were carried out on 620 of the original cohort recruited. The following measurements have been carried out: systolic blood pressure at rest and after exercise in the upper and lower extremities utilizing transcutaneous Doppler techniques; measurements of pulse volume of the extremities by segmental plethysmography and Doppler examination of the arteries; fasting plasma glucose, serum cholesterol and triglycerides, quantitative lipoproteins, platelet factor 4; circulating platelet aggregates; platelet aggregation studies; Ristocetin Willebrand factor and Willebrand antigen. Measurements of glycosylated hemoglobin and 2,3 diphosphoglycerate have been added to the study protocol for the years 03-04 and 05. Clinical data have been abstracted on all subjects for both study periods. Platelet survival studies were carried out in 75 of this original cohort. The additional 33 patients were recruited in year 03 for the first time for a platelet survival test. Preliminary observation indicates that the Vascular Laboratory assessment of occlusive arterial disease in the lower extremities is much more sensitive than clinical assessment of the peripheral pulses. The platelet survival test appears to be an excellent predictor of arteriosclerotic vascular disease. Ristocetin Willebrand factor and Willebrand antigen levels are increased in individuals with arteriosclerotic vascular disease regardless of whether diabetes is present or not. The comparison of the data collected on the same cohort during three different study periods will provide the basis for a descriptive analysis of the natural history of the progression of arteriosclerotic vascular disease in the diabetic. Changes which occur over time in any of the parameters measured may provide clues to mechanisms involved in the development of atherosclerotic lesions in the diabetic. It may point the way to new modes of treatment for this crippling complication of diabetes.